A portable media device can store media assets, such as audio tracks, video tracks or photos that can be played or displayed on the portable media device. Examples of portable media devices are the iPod® and the iPhone™ portable media devices, which are available from Apple Inc. of Cupertino, Calif. In addition to storing and playing media assets, the portable media device can have the capability to determine where the device is located. For instance, the device can be equipped with Global Positioning System (GPS) capability, cellular phone tower triangulation capability, or the like.
A portable media device can include one or more connectors or ports that can be used to interface with other devices. For example, the connector or port can enable the portable media device to couple to a host computer, be inserted into a docking system, or receive an accessory device. In the case of the iPod®, e.g., a vast array of accessory devices have been developed that can interconnect to the portable media device.
A number of portable GPS-enabled devices are currently available. GPS-enabled devices are used in a variety of applications like vehicle navigation, vehicle locating service, surveying, pet and people location determination etc. These devices generally derive location data from a constellation of 27 earth-orbiting satellites using a method called trilateration. The orbits of the satellites are arranged so that at any time, anywhere on Earth, at least four satellites are “visible” in the sky. Each GPS satellite transmits data that indicates its location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. The signals, moving at the speed of light, arrive at a GPS-enabled receiving device at slightly different times because some satellites are farther away from the GPS-enabled device than others. A GPS-enabled receiving device detects the signals from least four of the GPS satellites. The receiving device can then determine its distance to each of the detected satellites based on the differences in arrival times of the signals from the satellites. The receiving device can compute its own location based on the distance information determined.